As our population ages, neurodegenerative diseases are a growing problem, and trinucleotide repeat diseases are increasingly important. This is a proposal to determine the mechanism of motor neuron degeneration in Spinal and Bulbar Muscular Atrophy (SBMA) or Kennedy's disease, in which repeat expansion in the androgen receptor (AR) gene causes polyglutamine tract expansion in AR protein (termed ARK henceforth). First AR and ARK expression and localization will be compared in transfected cells through RNA and protein quantification, and immunohistochemical methods. Receptor binding to HSP9O, hormone response and regulation of transcription at known hormone response elements will be assayed. A yeast two hybrid screen and interaction cloning will be select proteins that bind ARK in vivo and vitro. ARK expressed in cultured cells will be used to study early cell death. and transgenic mice will be constructed with human ARK to establish an animal model. This research will be conducted with Keith R. Yamamoto, PhD, who cloned the glucocorticoid receptor (GR) and has described many aspects of steroid receptor function in molecular detail, including HSP9O association, hormone binding, transcriptional regulation, transcription factor interactions, and three dimentional protein structure. His laboratory has developed broad expertise in mammalian cell culture, yeast genetics, and protein biochemistry. Keith is a leader in fundamental research and scientific education. This proposal stemmed from my experience as a neurology resident, a fascination with trinucleotide repeat disease, and previous research experience with Keith on GR regulation through interactions with other factors. Initially I hope to to clarify molecular mechanisms of neurodegeneration in SBMA while broadening my knowledge of molecular and cellular biology, neuroscience and neurodegenerative diseases, While I conduct research I will attend basic science courses and journal clubs. Neurology departmental lectures, and outside courses on neurodegenerative diseases and transgenics. Ultimately I hope to become an academic investigator focused on mechanisms of neurodegenerative disease. By combining an important clinical problem with a strong basic science environment I will use a well defined protein as a tool to understand the molecular basis of the progressive motor neuron degeneration of SBMA.